Conventionally, contactless power supply systems for charging the batteries of electric automobiles or plug-in hybrid cars have been developed. One of such systems includes a secondary coil (receiver coil) 102 of a contactless power supply transformer mounted on a vehicle floor and a primary coil (transmitter coil) 202 provided on the ground which oppose each other to supply power from the ground to a stopping vehicle in contactless manner, as shown in FIG. 13.
The following patent document 1 (Japanese Patent Laid-open Publication No. 2010-172084) discloses the use of a double-sided coil formed of a plate-like ferrite core 10 around which a wire 11 is wound, as shown in FIG. 14, aiming for raising a tolerance for misalignments or gap variations between a primary coil and a secondary coil of the charging system and downsizing the coils. In this double-sided coil, a primary magnetic flux passes through the ferrite core 10, entering and exiting into/from magnetic poles at both ends.
The following patent document 2 (Japanese Patent Laid-open Publication No. 2012-175793) discloses a coil including a H-shaped ferrite core, as shown in FIG. 15, which has been developed for further reducing the size and weight of the double-sided coil. In this coil a wire 11 is wound around the portion of the H-shaped core corresponding to a transverse bar while the parallel portions of the H-shaped core at both sides work as magnetic poles.
The patent document 2 further discloses that the tolerance for misalignments is set to be larger along the line (x-direction) parallel to both magnetic poles than along the line (y-direction) orthogonal to the magnetic poles.
Currently, electric automobiles face a problem in a relatively short driving range per charging because of a battery performance. In view of solving the problem, various kinds of contactless power supply systems for running vehicles have been devised.
The following patent document 3 (Japanese Patent Laid-open Publication No. 2011-166992) discloses a system in which multiple power supply devices each including an AC source, a high-frequency power driver, a primary coil, a primary self-resonance coil, a power sensor, and an ECU are installed on a driving route to supply power to running vehicles having receiver coils.
The following nonpatent literature 1 (Jin Wook Kim et al., “Wireless power transfer for free positioning using compact planar multiple self-resonators” 2012 IEEE MTT-S International IMWS-IWPT 2012 pp. 127-130) has studied the characteristics of multiple resonators represented by the equivalent circuit in FIG. 16, which are placed following the source coil of a power supply device as shown in FIG. 17, aiming for elongating the power supply intervals of individual power supply devices.
The nonpatent literature 1 reports that as shown in FIG. 18, “dead zones” in which the power supply to secondary coils is interrupted still appear on the primary coils even when closely arranged with no gap as shown in FIG. 17.
The present invention has been made in view of such situations. It is an object of the present invention to provide a contactless power supply system of which a primary side (on the ground) can be installed by simple work and which can ensure longer power supply intervals.